Electric field gradient in copper alloys

The electric field gradient q and asymmetry parameter eta are calculated for non-magnetic dilute copper alloys. Both the valence and size-effect contributions are evaluated explicitly. The transition metal model potential theory is used to evaluate the contribution from the valence effect. The formalism due to Sagalyn and Alexander (1977) is adopted to evaluate the size-effect contribution. Only the size-effect parameter lambda is introduced to explain q and eta , whose calculated values are found to be in close agreement with the experimental values. The effective hardness of fourth row impurities is found to be larger than that of the fifth row impurities. The magnitudes of q and eta are found to be proportional to the effective charges on impurities if the evaluation of these charges includes both the size effect and bound state.